This invention relates to a congestion control technology in a computer network, specifically, a congestion control method for a packet-switched network.
Currently routers used in the Internet are weak in congestion control. Packet loss information is the only network congestion signal provided to the terminal. Network traffic is controlled by the terminal at the transport layer or the application layer. The networks are lack of appropriate policing ability. Recent breakpoint-resume and multi-threaded downloading technologies present challenges to the stability and the fairness of the Internet.
Core-Stateless Fair Queuing (CSFQ) is a technique for enhancing congestion control at the network layer. In CSFQ, edge routers measure and label the flow rate in the packet header. Packets having the same source and destination IP addresses are usually classified into a same flow. Core routers adaptively adjust the parameter of the fair bandwidth according to the congestion state at the output port. The core router can calculate reception probability of a packet using the fair bandwidth and the flow rate in the packet header. The core routers adaptively adjust the parameter of the fair bandwidth according to the congestion state at the output port. The edge routers can therefore provide differentiated services using bandwidth-weighted flow rates based on the access bandwidth. The CSFQ technique, however, has several shortcomings: firstly, the technique is unable to provide fair services in the presence of Bit-Torrent (BT) downloading. A single BT downloading includes multiple destinations. CSFQ cannot properly restrict the total throughput of a BT download because CSFQ identifies a flow only by its source and destination addresses. A BT download can thus increase its own throughput by increasing the number of sessions at the sacrifices of the throughputs of other traditional applications. BT downloads thus affect the fairness and the stability of the Internet. Moreover, due to lack of trust between different domains, flows are measured and re-labeled at the domain border, which becomes a performance bottleneck. Furthermore, for inter-domain measurements and re-mark rate of conversation, the bandwidth weights of the flows are inevitably lost. The bandwidth weight is in effect only inside its domain and cannot be credibly passed on to other domains, which limits the flexibility of CSFQ.